To meet the demand for wireless data traffic having increased since deployment of 4G communication systems, efforts have been made to develop an improved 5G or pre-5G communication system. Therefore, the 5G or pre-5G communication system is also called a ‘Beyond 4G Network’ or a ‘Post LTE System’.
The 5G communication system is considered to be implemented in higher frequency (mmWave) bands, e.g., 60 GHz bands, so as to accomplish higher data rates. To decrease propagation loss of the radio waves and increase the transmission distance, the beamforming, massive multiple-input multiple-output (MIMO), Full Dimensional MIMO (FD-MIMO), array antenna, an analog beam forming, large scale antenna techniques are discussed in 5G communication systems.
In addition, in 5G communication systems, development for system network improvement is under way based on advanced small cells, cloud Radio Access Networks (RANs), ultra-dense networks, device-to-device (D2D) communication, wireless backhaul, moving network, cooperative communication, Coordinated Multi-Points (CoMP), reception-end interference cancellation and the like.
In the 5G system, Hybrid FSK and QAM Modulation (FQAM) and sliding window superposition coding (SWSC) as an advanced coding modulation (ACM), and filter bank multi carrier (FBMC), non-orthogonal multiple access (NOMA), and sparse code multiple access (SCMA) as an advanced access technology have been developed.
One type of wireless network topology comprises one or more wireless transceivers, known as base stations, where each base station provides network coverage over a certain geographic area, known as a cell. A device located within a certain cell may connect to the network by connecting to a corresponding base station through a wireless link. When a device connected to the network moves within a cell, the device typically remains connected to the corresponding base station. On the other hand, when a device connected to the network moves from a first cell to a second cell, a handover process is performed, wherein the device disconnects from the base station of the first cell and connects to the base station of the second cell.
In a network topology of the type described above, each device connected to the network typically transmits a Channel Quality Indicator (CQI) to the base station to which each device is currently connected. The CQI of a device provides an indication of the quality of the channel between that device and the base station, and may be used, for example, to determine or select the most appropriate or optimal transmission parameters (e.g. data rate and modulation and coding scheme) for downlink data transmissions from the base station to the device. Since channel conditions may vary over time, a device typically transmits updated CQIs repeatedly to the base station so that the base station can maintain reliable or up-to-date CQIs. For example, updated CQIs may be transmitted periodically, according to a certain schedule, or in response to a request from the base station.
A wireless network topology of the type described above has been applied to mobile telecommunications for more than twenty years. More recently, the concept of an Internet of Things (IoT) has been developed. An IoT is envisioned as a network to which a very large number of devices, including a very wide variety of devices, may be connected. In particular, the concept of an IoT extends network connectivity to many types of devices that traditionally have not been connected to a network, for example home appliances (e.g. fridges, vacuum cleaners, televisions) and utility meters (e.g. gas, water and electricity meters). An IoT has many potential applications, including allowing connected devices to collect and exchange data, and allowing connected devices to be remotely controlled and monitored, for example. It is anticipated that an IoT may be implemented, at least partially, using a wireless cellular network (forming a Cellular IoT, or CIoT), and the technical requirements of a CIoT implementation are being considered in the development of the next generation mobile telecommunications standard, 5G.
A document titled 3GPP TR 45.820 V2.1.0 describes the outcomes of a 3GPP study item on “Cellular System Support for Ultra Low Complexity and Low Throughput Internet of Things”. This document mentions that “To support the so called ‘Internet of Things’ (IoT), 3GPP operators have to address usage scenarios with devices that are power efficient (with battery life of several years), can be reached in challenging coverage conditions e.g. indoor and basements and, more importantly, are cheap enough so that they can be deployed on a mass scale and even be disposable.”
Many devices connected to a CIoT may have very strict battery life requirements. For example, some devices may require a battery life of up to 10 years. Consequently, such devices are required to operate with long periods of discontinuous reception (DRX) and discontinuous transmission (DTX) to save power and extend battery life. Consequently, such devices may only transmit updated CQIs relatively infrequently.
In this case, one problem that can arise is that, due to long periods between CQI updates, a most recent CQI may become unreliable or out-of-date, before an updated (and hence more reliable) CQI is provided. This problem is particularly acute in situations where channel conditions may vary significantly over time, for example for mobile devices, or stationary devices located in varying environments. Selecting transmission parameters based on unreliable or out-of-date CQIs can lead to poor transmission performance, or even transmission failure, due to the selection of sub-optimal transmission parameters based on out-of-date CQIs.
In some situations, it is necessary for a base station to transmit data for reception by multiple devices simultaneously (i.e. a multicast transmission), for example to distribute a software update or patch to multiple devices at once. In this case, as the number of devices increases, the probability of at least one device having an out-of-date CQI, and hence the probability of transmission failure to at least some of the devices, increases.
In view of the above, what is desired is a technique for selecting appropriate data transmission/reception parameters based on CQIs of devices in a network, and a technique for updating the CQIs, to improve transmission/reception performance, while adhering to the battery life requirements of the devices.
The above information is presented as background information only to assist with an understanding of the present disclosure. No determination has been made, and no assertion is made, as to whether any of the above might be applicable as prior art with regard to the present disclosure.